Add a --hfa-name command that allows one to specify the unique opname for a hashfast device.
Document the hfa-name feature
Remove ENV from hashfast udev rules.
Merge pull request #554 from xiangfu/avalon2

Avalon2: decode the voltage
Add to udev rules hfa devices for firmware writing.
Enable the hfa shed supported feature by default.
Icarus - ignore HW errors in hash rate ... and fix detection of them
Allow the drop in MHz per hfa failure to be specified on the command line.
Fix harmless warning.
Don't break out of hfa_old_device early if there's no serial number.
Make hfa resets properly inherit across a shutdown.
Use op_name if possible first with hfa devices to detect old instances and be able to choose the starting clockspeed before sending an init sequence, reverting to setting op name and serial number as fallbacks.
Document the hfa-fail-drop command.
Update README with all command line options.
Display the base clockrate for hfa devices with a different name to per die clockrates to be able to easily distinguish them.
Add shed count to hfa API stats output.
Read in hfa stream until we get a HF_PREAMBLE
Update NEWS
Issue a usb_nodev on a bad work sequence tail in hfa
Only start one hfa device at startup, leaving the rest to hotplug.